To my knowledge, some trap cards cannot be activated during the battle phase. For example, you cannot use Torrential Tribute or Bottomless Trap Hole to prevent a pyramid turtle summon. Would Compulsory work in this situation? Do other cards also fall under this category? If so, how can you tell?

To my knowledge, some trap cards cannot be activated during the battle phase. For example, you cannot use Torrential Tribute or Bottomless Trap Hole to prevent a pyramid turtle summon. Would Compulsory work in this situation? Do other cards also fall under this category? If so, how can you tell?

That's not right, Torrential Tribute and Bottomless Trap Hole CAN be activated in the Battle Phase, it's during the Damage Step that they cannot be activated, and the Damage Step is precisely where Pyramid Turtle activates it's effect.

If you wanna know more in detail about this, i suggest reading the sticky, more specifically the "Battle Phase Game Mechanics" section and the "Things that can be activated in the damage step" section.

BTW, Compulsory Evacuation Device can be activated in the Battle Phase, just like almost every trap, but it cannot be activated in the Damage Step because it doesn't fit the criteria.

So if I were to prevent a pyramid turtle's summoning I would have to have a Rai-oh, something that will remove the pyramid turtle from play, etc. Correct?

Rai-Oh cannot negate the summon that Pyramid Turtle will produce because it happens during the resolution of a chain, you will need a card that negates monster effects (like Divine Wrath or Herald of Orange Light), or a card that negates effects that produce summons (however, Royal Oppression cannot be activated in the damage step).